1. Field of the Invention
This invention relates to a collision detection sensor to detect the collision of a vehicle and a collision object by converting the collision stress into a change in optical transmission characteristics of an optical fiber.
2. Description of the Related Art
It is considered to improve the safety of pedestrians by placing the collision detection sensor to detect the collision with the collision object (e.g., a pedestrian) on the periphery (e.g., a bumper) of a vehicle.
A collision detection optical fiber sensor is known which detects a collision by converting the collision stress into a change in the optical transmission characteristics of an optical fiber. For instance, the collision detection optical fiber sensor is constructed such that a plurality of holes are provided in a longitudinal direction on a metallic stress concentration board, the optical fiber is arranged along the stress concentration board, and the stress concentration board and the optical fiber are covered with a molding material. According to this, when collision force presses the optical fiber against the stress concentration board, the optical fiber is bent at both edges of the hole. Thereby, an increase in transmission loss due to the bending can occur in accordance with the collision force.
The related art to the invention is, e.g., JP-A-2002-531812.
In the above collision detection optical fiber sensor, it is necessary to use the metallic stress concentration board made of iron etc.